1. Field of the Invention
The invention relates to a vehicular headlamp apparatus and, more particularly, to a vehicular headlamp apparatus used in an automobile, or the like.
2. Description of the Related Art
As a related art, there is proposed a vehicular headlamp apparatus that accommodates a lamp unit in a lamp chamber defined by a lamp body and a translucent cover. The lamp unit has a semiconductor light-emitting element as a light source. For example, Japanese Patent Application Publication No. 2008-226706 (JP-A-2008-226706) describes a configuration in which three LEDs are uniformly arranged on an outer peripheral portion of a substantially cylindrical or substantially hemispherical lamp unit. In this configuration, an oblique cut portion is formed by a first semiconductor light-emitting element, a diffusion portion having a horizontal cut-off line is formed by a second semiconductor light-emitting element, and then these semiconductor light-emitting elements are used in combination to form a low beam light distribution pattern. In addition, a high beam light distribution pattern is formed by a third semiconductor light-emitting element. Thus, different partial light distribution patterns are respectively formed by the plurality of semiconductor light-emitting elements and then those semiconductor light-emitting elements are used in combination to form a light distribution pattern. By so doing, it is possible to compensate for an insufficient amount of light of the semiconductor light-emitting elements or form light distribution patterns having various shapes.
In recent years, with a change in design of a vehicle, a vehicular headlamp apparatus that includes a translucent cover slanted in a vehicle longitudinal direction has been frequently employed. When the vehicular headlamp apparatus having a slanted translucent cover accommodates the above described substantially cylindrical or substantially hemispherical lamp unit, a lamp unit is arranged so as to protrude by a large amount toward a vehicle body with respect to a slanted surface of the translucent cover. Therefore, the size in a substantially vertical direction with respect to the slanted surface of the translucent cover, that is, the size in the depth direction, increases in the vehicular headlamp apparatus and, therefore, the size of the vehicular headlamp apparatus increases.